In storage apparatuses using storage media such as magnetic disks, optical magnetic disks, optical disks, and the like, format processing operations that preliminarily initialize storage media are necessary for utilizing the storage media for reading and writing data. Examples of the format processing operations include physical formatting in which a digital signal sequence in a storage medium is rewritten with a specified pattern so that the storage medium can be read and written by a storage apparatus, and logical formatting in which a data area is partitioned in units of processing performed by a host OS (for example, in units of blocks) and identified.
The physical formatting is an initializing process in which a medium is formatted in units of tracks, and the logical format means a formatting process in which a data area in a physically formatted track is formatted in units of blocks. In the logical format, usually, it takes a long time (for example, more than or equal to 30 minutes) to complete the formatting process with respect to all blocks in the medium. Therefore, when a storage medium is used, it is necessary to wait for a long time for the completion of formatting performed in the formatting process preliminarily carried out as an initializing process.
On the other hand, for example, there has been a technique where, when an access request made by a host computer or the like is a request directed to an area in which formatting is not completed, logical formatting is executed for the area first, and then the access the request of which is accepted is performed, thereby enabling the access request from the host computer or the like to be accepted even if a storage medium is, after being connected, in a state in which logical formatting is not completed. Accordingly, the host computer can make an access request to the connected storage medium before the completion of the logical formatting. Example of documents of the related art include Japanese Laid-open Patent Publication No. 2003-29933, Japanese Laid-open Patent Publication No. 2003-29934, and Japanese Laid-open Patent Publication No. 2003-241904. However, in the above-mentioned techniques, there is a problem that, when a host computer makes an access request, logical formatting and an access operation are sequentially performed, and hence the load of processing performed in a storage apparatus and a load on a storage medium become large owing to the increase of the number of times the storage medium is accessed. In addition, when an access request directed to an storage area the formatting of which is not completed is accepted from the host computer, a processing operation or the like for evacuating data for the access request is added compared with a processing operation for a normal access request, and hence a time necessary for the processing of the access request increases, thereby the processing of the access request being delayed. Therefore, it is desirable to transfer, as quickly as possible, the storage medium to a state in which format processing is completed.